Electrical switches and variable electrical resistance mechanisms are utilized in many different applications in order to, in effect, undergo and operatively sense or determine a positional change in response to movement of an operatively associated movable member, and furthermore, to provide or generate a corresponding electrical signal, indicative of such positional change, to an electrical controller. An exemplary use of such switches and variable electrical resistance mechanisms is in conjunction with an accelerator pedal of an electric vehicle whereupon depression of the accelerator pedal, the variable electrical resistance mechanism will generate an electrical signal which varies in proportion to the displacement or depression of the accelerator pedal which, of course, corresponds to the degree of acceleration desired by the vehicle operator.
The variable resistance mechanism, as is normally the case with a potentiometer or other similar variable electrical resistance devices or mechanisms, is mechanically linked to the movable member so as to sense or determine the displacement or movement of the movable member over a predetermined range of movement. More particularly, in the case of utilizing such a system in connection with an accelerator pedal of an electric vehicle, the aforenoted related U.S. patent application Ser. No. 08/603,041 discloses a system wherein a potentiometer shaft is operatively connected to an arm or the like which extends from the accelerator pedal so as to be rotated in response to the depression or displacement of the accelerator pedal, and a lever or actuator, carrying a wiper element for defining a wiping contact with respect to constant and variable electrical resistance elements disposed upon a printed circuit board of the electrical assembly, is provided upon the rotary shaft.
The aforenoted system, more specifically disclosed within the aforenoted related U.S. patent application Ser. No. 08/603,041, is illustrated in FIGS. 1 and 2 of the drawings of the present patent application, wherein such drawing FIGS. 1 and 2 of the present patent application correspond to FIGS. 1 and 2 of the aforenoted related U.S. patent application Ser. No. 08/603,041 drawings, however, the details and description of the illustrated and disclosed system of the aforenoted related U.S. patent application Ser. No. 08/603,041 are only briefly described hereinbelow, and only the relevant component parts of the system have been designated by reference characters, as is necessary to the understanding of such a related system for background purposes of this patent application and the invention more fully described later herein. More particularly, the referenced system is generally indicated by the reference character 10 and comprises a normally-open switch 20 which is disposed within a housing 100, and a printed circuit board 300, upon which is disposed a constant electrical resistance element 32 and a variable electrical resistance element 34, which is also disposed within the housing 100. An actuator body member 220, which has mounted thereon wiper elements 420 for wipingly engaging the constant electrical resistance element 32 and the variable electrical resistance element 34, is pivotally disposed within the housing 100 as a result of being fixedly mounted upon a rotatable shaft 60 by means of a sleeve portion 230. The sleeve portion 230 of the actuator body member 220 is axially or longitudinally fixed upon or with respect to the shaft 60 by means of a collar 70 and a set screw 74, wherein the set screw 74 extends through a threaded bore 72 defined within the collar 70 so as to engage the shaft 60. The shaft 60 is, of course, operatively connected to the movable member or accelerator pedal, not shown. A torsion spring 170 biases the actuator body member 220 toward the position illustrated in FIG. 1 such that the actuator body member 220 is normally engaged with an actuator push-button 22 of the normally-open switch 20.
While the aforenoted system has in fact proven to be quite satisfactory from an operational point of view in that the same achieves its operational objectives in a reliable manner in order to properly control, for example, the acceleration mode requirements of the associated electric vehicle, it is often desirable, particularly in connection with the operation of electric vehicles, that the accelerator pedal be permitted to undergo a predetermined amount of limited travel or depression by the vehicle operator prior to electrical power actually being generated and delivered or transmitted to the drive train of the vehicle. Considered from a different operative perspective, it is desirable that the deliverance or transmission of actual electrical power to the vehicle drive train be effectively delayed for a predetermined amount of time after the accelerator pedal has undergone a predetermined amount of displacement, movement, or depression by the vehicle operator, wherein such predetermined amount of delayed power transmission time also encompasses a corresponding predetermined amount of pivotal or arcuate movement or displacement of the actuator body member and the wiper elements carried thereon with respect to the constant and variable electrical resistance elements of the printed circuit board prior to the closing of the normally-open switch mechanism. There are several reasons for achieving such a mode of operation. Firstly, such a mode of operation effectively limits any sudden "lurching" of the vehicle when the vehicle is initially moved from a stopped condition or state which would otherwise occur if electrical power is instantaneously transmitted or delivered to the vehicle drive train, without any predetermined delay, when the vehicle accelerator pedal is depressed by the vehicle operator. Viewed from a slightly different perspective, the incorporation of such a delay or operative mechanism within the vehicle comprises, in effect, a safety feature whereby acceleration or movement of the vehicle from a stopped position or condition cannot be inadvertently achieved merely as a result of incidental or limited contact or depression of the vehicle pedal. Secondly, such a mode of operation is desirable from an ergonomic point of view. Thirdly, such a mode of operation permits adjustability of the voltage signal output level as a function of the movement or depression of the vehicle accelerator pedal, and still further, or fourthly, such a mode of operation or use of such a delay or operative mechanism permits the pedal travel, movement, or depression to be adjusted or compensated for so as to permit the system to be operative in connection with different basic switch mechanisms or assemblies.
In addition to the foregoing, it sometimes happens that the normally-open switch mechanism will undergo or experience shock or impact forces if the accelerator pedal is suddenly or quickly released whereby the actuator body member is returned to its initial arcuate position and into engagement with the push-button element of the switch mechanism in a substantially rapid manner under the biasing influence of the torsion spring. Under such circumstances, it is possible that the normally-open switch mechanism could undergo or experience breakage, damage, distortion, and the like, and in a similar manner, stresses are likewise imposed upon the solder joints that secure the switch mechanism upon the printed circuit board.
A need therefore exists in the art for a new and improved accelerator module for an electric vehicle which incorporates therein a variable resistance control mechanism, assembly, or arrangement wherein the transmission of electrical power to the drive train of the electric vehicle is effectively delayed for a predetermined amount of time during which the vehicle accelerator pedal, and the actuator body member operatively connected thereto, can undergo an initial displacement or movement whereby accelerated movement of the electric vehicle from an initially stopped condition or state can be accomplished in accordance with a desired acceleration curve and in a safe manner, and in addition, impact, shock forces, and stresses, upon the switch mechanism, and its mounting joints upon the printed circuit board, can be effectively eliminated or substantially reduced.